The UK National Oceanography Centre (NOC) in Liverpool recently published a study, according to which potential energy gains from tidal power by the use of pumping process are “too optimistic”.
Tidal energy is still in its emerging phase, so tidal range structures (barrages, lagoons, and offshore tidal impoundments) require large financial resources. Investment into the industry can be encouraged by improvement of the financial side, including the pumping process.
The study results were published in Renewable Energy scientific journal, and differ from some previous theoretical studies.
Researchers found out that with suitable pump and turbine efficiencies a greater height potential, created by the increased water level difference between the tide and the water behind the structure, can result in net energy gains regardless of the energy expended in pumping.
“The theoretical studies are a valid way of calculating the maximum potential energy gains, but these are based on first principles – the water would have to drop instantaneously to achieve the previously reported figures, and hence are not achievable in practice,” said Dr Nicholas Yates, NOC scientist and lead author of the paper .
“We had not seen any attempts to systematically explore the factors involved in pumping with tidal range power generation and this is something we set out to address.”
Offshore WIND Staff, January 13, 2014; Image: Wikimedia (La Rance tidal barrage in France)